purescript ->>= 在纯脚本中是什么意思？

Question

我正在阅读 purescript wiki并找到以下部分解释 do根据 >>= .
>>= 是什么意思意思是？

Do notation

The do keyword introduces simple syntactic sugar for monadic expressions.

Here is an example, using the monad for the Maybe type:

 maybeSum :: Maybe Number -> Maybe Number -> Maybe Number 
 maybeSum a b = do   
     n <- a
     m <- b   
     let result = n + m   
     return result 

maybeSum takes two values of type Maybe Number and returns their sum if neither number is Nothing.

When using do notation, there must be a corresponding instance of the Monad type class for the return type. Statements can have the following form:

• a <- x which desugars to x >>= \a -> ...
• x which desugars to x >>= \_ -> ... or just x if this is the last statement.
• A let binding let a = x. Note the lack of the in keyword.

The example maybeSum desugars to ::

 maybeSum a b =
   a >>= \n ->
     b >>= \m ->
       let result = n + m
       in return result

Answer 1

>>=是一个函数，仅此而已。它位于 Prelude 模块中，类型为 (>>=) :: forall m a b. (Bind m) => m a -> (a -> m b) -> m b ，是 bind 的别名Bind 的功能类型类。您可以在 this link 中找到 Prelude 模块的定义。 ，在 Pursuit package index 中找到.

这与 Monad 密切相关。 Haskell 中的 type 类，它更容易找到资源。有一个famous question on SO关于这个概念，如果你想提高对绑定(bind)函数的了解，这是一个很好的起点(如果你现在开始学习函数式编程，你可以暂时跳过它)。